1. Identify the Problem:
* All turn signals non-functional (front and rear, left and right): This usually points to a more significant problem in the electrical system, possibly a blown fuse, faulty flasher relay, or a problem with the turn signal switch.
* Only one side non-functional (left or right): Suggests a problem on that specific side, like a burned-out bulb, bad connection, or a fault in the wiring harness on that side.
* Hazard lights work, but turn signals don't: This strongly indicates a problem with the turn signal switch stalk or its wiring.
* Intermittent turn signals: This could be caused by loose connections, corroded wiring, or a failing flasher relay.
2. Check the Easy Stuff First:
* Bulbs: Start by visually inspecting all turn signal bulbs (front and rear, left and right). Replace any burned-out bulbs. Remember, a bad bulb can sometimes cause the entire system to malfunction (though less likely on newer vehicles). Use the correct wattage bulb specified in your owner's manual.
* Fuses: Check your owner's manual to locate the fuse(s) for the turn signals. Use a test light or multimeter to check if the fuses are blown. Replace any blown fuses with the correct amperage. Don't replace a fuse with a higher amperage fuse, this is a fire hazard.
* Flasher Relay: Locate the flasher relay (often under the dash or in the fuse box). You can often swap it out with a spare (if available) or purchase a replacement. It's a relatively inexpensive part. The clicking sound from the relay is often a key indicator that it's functioning. If there's no click, it's a prime suspect.
3. More Advanced Troubleshooting:
* Wiring Harness: If fuses, bulbs, and flasher relay are okay, you may have a break or short in the wiring harness. This requires visual inspection of the wiring, checking for any frayed wires, corrosion, or loose connections, especially near the turn signal switch, taillights, and front turn signal assemblies. Use a multimeter to check for continuity in the circuits. This is challenging and may require some electrical knowledge.
* Turn Signal Switch: A faulty turn signal switch is a common cause. Testing this component requires a multimeter and some electrical knowledge. Often, replacement is necessary as repairing them is difficult.
* Multi-meter Testing: If you have a multimeter, you can test the voltage at different points in the circuit to pinpoint the break or short. Consult a wiring diagram for your specific year and model of GMC Safari to identify the correct points to test.
4. Seek Professional Help:
If you're not comfortable working with automotive electrical systems, it's best to take your GMC Safari to a qualified mechanic or auto electrician. Diagnosing electrical problems can be tricky, and improper repairs can lead to further damage.
Important Notes:
* Safety First: Always disconnect the negative battery terminal before working on any electrical components in your vehicle.
* Wiring Diagram: Obtain a wiring diagram specific to your year and model of GMC Safari. This will greatly assist in troubleshooting the electrical system. These can often be found online (for a fee) or at an auto parts store.
* Owner's Manual: Your owner's manual should contain information about fuse locations and specifications for bulbs and other components.
This detailed approach should help you diagnose and hopefully repair your GMC Safari's non-working turn signals. Remember to take your time, be methodical, and prioritize safety.
